Draw press die assembly and method of using the same

Abstract

A draw press die assembly includes an upper die, a lower die positioned beneath the upper die, a blankholder for supporting an associated workpiece, and a blankholder drive mechanism connected with at least one of the upper die and the blankholder. The blankholder drive mechanism is configured to provide a pulsating movement of the blankholder with respect to the upper die.

The invention claimed is: 
     
       1. A blankholder of a draw press, the blankholder comprising:
 a main blankholder; 
 a sub blankholder movably connected to the main blankholder; and 
 a blankholder drive mechanism mounted directly to the main blankholder; 
 wherein the blankholder drive mechanism oscillates the sub blankholder relative to the main blankholder during operation of the draw press; 
 wherein during the operation of the draw press, the blankholder drive mechanism oscillates the sub blankholder with respect to an upper die of the draw press such that the upper die and the sub blankholder release an associated workpiece during each movement of the sub blankholder away from the upper die during the oscillation; 
 wherein the main blankholder and the sub blankholder directly contact each other at a common interface; and 
 wherein during the operation of the draw press, the main blankholder presses against the upper die other than through the sub blankholder. 
 
     
     
       2. The blankholder of  claim 1 , wherein the blankholder drive mechanism includes a spindle servo motor. 
     
     
       3. The blankholder of  claim 2 , wherein the spindle servo motor includes a spindle having a distal end engaging the sub blankholder. 
     
     
       4. The blankholder of  claim 1 , wherein:
 the sub blankholder includes an upper surface, and 
 during the operation of the draw press, the associated workpiece is positioned between the upper surface and the upper die. 
 
     
     
       5. The blankholder of  claim 1 , wherein the oscillation of the sub blankholder includes movements of the sub blankholder in a direction parallel to a direction in which the upper die is moved during the operation of the draw press. 
     
     
       6. The blankholder of  claim 5 , wherein the oscillation includes movements of the sub blankholder away from and towards the upper die. 
     
     
       7. The blankholder of  claim 6 , wherein the movements of the sub blankholder away from the upper die during the oscillation are effected by the blankholder drive mechanism. 
     
     
       8. The blankholder of  claim 1 , wherein the blankholder drive mechanism oscillates the sub blankholder at a frequency greater than 15 Hz. 
     
     
       9. A draw press die assembly comprising:
 an upper die; 
 a lower die positioned beneath the upper die; 
 a blankholder for supporting an associated workpiece, the blankholder including:
 a main blankholder, and 
 a sub blankholder movably connected to the main blankholder; and 
 
 a blankholder drive mechanism mounted directly to the main blankholder; 
 wherein the blankholder drive mechanism oscillates the sub blankholder relative to the main blankholder during operation of the draw press; 
 wherein during the operation of the draw press, the blankholder drive mechanism oscillates the sub blankholder with respect to an upper die such that the upper die and the sub blankholder release the associated workpiece during each movement of the sub blankholder away from the upper die during the oscillation; 
 wherein the main blankholder and the sub blankholder directly contact each other at a common interface; and 
 wherein during the operation of the draw press, the main blankholder presses against the upper die other than through the sub blankholder. 
 
     
     
       10. The draw press die assembly of  claim 9 , wherein:
 the blankholder drive mechanism includes a spindle servo motor; 
 the spindle servo motor includes a spindle having a distal end engaging the sub blankholder; 
 the sub blankholder includes an upper surface; 
 during the operation of the draw press, the associated workpiece is positioned between the upper surface and the upper die; and 
 during the operation of the draw press, the blankholder drive mechanism oscillates the sub blankholder with respect to the upper die. 
 
     
     
       11. The draw press die assembly of  claim 9 , wherein:
 the oscillation of the sub blankholder includes movements of the sub blankholder in a direction parallel to a direction in which the upper die is moved during the operation of the draw press; 
 the oscillation includes movements of the sub blankholder away from and towards the upper die; and 
 the movements of the sub blankholder away from the upper die during the oscillation are effected by the blankholder drive mechanism. 
 
     
     
       12. The draw press die assembly of  claim 9 , wherein the blankholder drive mechanism oscillates the sub blankholder at a frequency greater than 15 Hz. 
     
     
       13. A method of drawing a metal part comprising:
 moving an upper die in a downward direction toward the metal part positioned on a blankholder, wherein the blankholder includes a main blankholder, and a sub blankholder movably connected to the main blankholder; and 
 controlling a blankholder drive mechanism mounted directly to the main blankholder to oscillate the sub blankholder relative to the main blankholder during said moving the upper die in the downward direction, 
 wherein the oscillation of the sub blankholder includes movements of the sub blankholder away from and towards the upper die; 
 wherein the sub blankholder includes an upper surface; 
 wherein during said moving the upper die in the downward direction, the metal part is positioned between the upper surface and the upper die; 
 wherein said moving the upper die in the downward direction, the blankholder drive mechanism oscillates the sub blankholder with respect to the upper die such that the upper die and the sub blankholder release the metal part during each movement of the sub blankholder away from the upper die during the oscillation; 
 wherein the main blankholder and the sub blankholder directly contact each other at a common interface; and 
 wherein during the operation of the draw press, the main blankholder presses against the upper die other than through the sub blankholder. 
 
     
     
       14. The method of  claim 13 , wherein:
 the oscillation of the sub blankholder includes movements of the sub blankholder in a direction parallel to the downward direction in which the upper die is moved; 
 the oscillation includes the movements of the sub blankholder away from and towards the upper die; 
 the movements of the sub blankholder away from the upper die during the oscillation are effected by the blankholder drive mechanism. 
 
     
     
       15. The method of  claim 13 , wherein controlling the blankholder drive mechanism comprises controlling a spindle servo motor mounted directly to the main blankholder. 
     
     
       16. The method of  claim 13 , wherein the blankholder drive mechanism oscillates the sub blankholder at a frequency greater than 15 Hz. 
     
     
       17. The method of  claim 13 , wherein:
 the blankholder drive mechanism includes a spindle servo motor; and 
 the spindle servo motor includes a spindle having a distal end engaging the sub blankholder.